The Secret Life of War weaves in and out of several wars on several continents, but is essentially about fear. We all have different ways of conquering or confronting fear. For Peter Beaumont, the Observer's foreign affairs editor, it meant going to the places that scared him, into the heart of war for nearly two decades, exposing himself to danger and injury, even after he saw colleagues killed and injured. He became numbed to the suffering even as he meticulously recorded it. For Beaumont, reporting was not only his metier, but, in some way, his calling.

He began, like most of us, known as the "luckless tribe" by William Howard Russell, in the brutal series of backyard wars in the Balkans and continued to roam the world - Afghanistan, Iraq, Palestine, Lebanon. Along the way, he encountered visions of horror that most people never find in their nightmares: ambushes, firefights, the aftermath of suicide bombings, or being stuck on an American military base in Iraq "waiting for the bad stuff to happen".

Bad stuff happens often and with alarming intensity for Beaumont. But what separates his book from the dozens written by journalists - particularly after the 9/11 crisis bred a new generation of reporters who found war reporting "glamorous" (trust me, it is not) - is his honesty and his humility. He is able to diagnose his own need to return to war the way a junkie feeds on heroin. He also touches a sensitive subject that most of us don't want to face - post-traumatic stress disorder and its effect on war reporters - and tells us about his sessions with a counsellor.

It is a subject that needs to be addressed. In 2000, Canadian psychiatrist Anthony Feinstein began a research project with a group of us who reported war. He observed us like bugs under a microscope and the results were alarming to say the least: drug abuse, broken relationships, alcoholism and the inability to sustain any prolonged contact with "healthy" individuals (women were greater alcoholics than men). A predisposition to PTSD is often genetic, but it is clear the sustained proximity to war increases the rate sharply.

Beaumont is self-aware. He knows it is not normal to feel more alive in a war zone than real life, but he is helpless to contain his desire to be where the story is. One afternoon, he has lunch with a reporter turned human rights activist who gently prods him about his relationships and his drinking. He already knows his state of mind isn't healthy, but he cannot help feeling: "Who am I if I am not in war zones?" He mourns his lack of time with his two children, the lack of attention to his wife.

Beaumont writes beautifully, and calmly, even when describing the fiercest and most emotive moments of war. It is a book from the heart, not a military analysis and certainly (thank God) not another book about America's failure in Iraq or the occupation. He allows the reader into a hallowed environment where friends bond for life, because they nearly die together. And as readers, we watch him grow and change and eventually face the music: is this it for the rest of my life?

There comes a point for most war reporters when we leave it all behind. One night, Beaumont lets a 60-year-old reporter share his floor in the West Bank while on assignment. The man is respected in his field, but Beaumont has an epiphany that this is not who he wants to be when he grows up. That epiphany is crucial. Mine came staring down a column miles long of dead bodies in Congo and realising that I felt nothing at all. A colleague once told me she quit when she realised she was writing the same line to describe rape victims, no matter where the war was: "She wore a yellow tracksuit... it was covered in blood."

At the end of this haunting book, a pensive Beaumont contemplates his future, with a new partner. He has a chance, he feels, to move ahead without the nightmares, the adrenaline kick faster than any drug, the inevitable collateral damage to family and friends. He's not sure where he is going, but he knows he is glad to be alive. Witnessing Beaumont's painful metamorphosis, one realises the book was a tremendous catharsis, a way for him to write his way out of the blackness. You close it and can only wish him peace.